Starting device for internal-combustion engines



Aug. 20, 1929.

F. KESSELRING I 1,724,941 STARTING DEVICE FOR INTERNAL COMBUSTION ENGINES Filed Sept. 10, 1927 2 Sheets-Sheet l HHH Jnvenfor:

Aug. 20, 1929, F. KESSELRING 1,724,941

STARTING DEVICE FOR INTERNAL COIBUSTION ENGINES Filed Sept. 10, 1927 2 Shoo'tHheet v2 Patented Aug. 20, 1929.

FRITZ KESSELRING, OF FURTH, GERMANY.

STARTING DEVICE FOR INTERNAL-COMBUSTION ENGINES.

Application filed September 10, 1927. Serial No. 218,614.

My invention refers to an electric starter for internal combustion engines, especially for motor cars, and particularly to a starter of the type comprising for its main parts: An electric motor, a pinion and a screw gear to push the pinion in and out of mesh'with the toothed fly Wheel of the engine.

As the'general arrangement and working method of the parts of such a starter are well known to experts, I do not need to describe them here in detail. In order, however, to make the following description of my invention more clear I will make a few introductory remarks about the parts of the known type.

Of the two parts of the screw gear, spindleand nut, one is connected to the electric motor and the other to the pinion. The part connected to the electric motor I will term the pushing screw member and the other the pushed screw member. The axial movement of the screw gear by means of which the pinion is brought into mesh with the fly wheel of the engine I term the advance and consequently the reverse movement I call the return of the pushed screw member. The position in which the pushed screw member lies when the starter is at rest I term the initial position, and the position into which the pushed screw member comes at the end of its advance I term the end position of the same screw member.

There pertain to the known devices of the type in question first of all those, the function of which depends upon the friction or upon the inertia of the pushed screw member. The function of these devices is not quite reliable by reason of the variableness of the friction, or it requires a considerable mass for the pushed screw member and for the pinion whereby the weight ofthe device is increased and, owing to the pushes of this mass as occurring, as a rule, during the service, the wear and tear of the device is accelerated.

In order to obviate these drawbacks it has already been proposed to combine a return spring adapted to counteract the forward movement of the pushed screw member from its initial position with a stop mechanism dependentupon the rotatory movement. of said member. the object being either to prevent, orto limit to a certain small amount, the rotation of the pushed screw memberduring the first part of its forward movement. from standstill into its initial "position.

This latter starting device depends neither upon the friction, nor upon the inertia of the pushedscrew member, but suffers from the following two drawbacks:

1. hen the starting procedure is initiated atthat point of time at which the flywheel of the explosion motor is still in motion, the pinion can be caught by the teeth of the fly-wheel as long as the stop mechanism prevents it from rotation and either a tooth or said mechanism breaks.

2. If the starting device is used in connection with a combined ligl1ting-starting-machine, and on the one side this machine is to be coupled with the fly-wheel of the explosion motor by the intermediary of the starting device, and on the other side said machine is connected permanently with the explosion motor and a free-wheel mechanism is inserted into the connection, there then takes place what follows: When the explosion motor is disconnected and its number of revolutions decreases more and more, the stopmechanism becomes again active at a certain small number of revolutions of the lighting machine, the pinion is again advanced, and there arises meshing with the still rotating fly-wheel, whereas the pinion is prevented from rotation by the stop mechanism, in consequence whereof also in this case either a tooth or the stop mechanism is broken.

Now, the subject-matter of the present invention relates to a starter of the second kindwhich, however, does not suffer from the drawback stated and is, moreover, particularly simple. This improved starter is, therefore, adapted for use also in connection with an electric machine which not only can serve as motor during the starting period, but also as generator for charging a storage battery when it is driven by the engine for instance of a motor-car. If the starting motor 'of the engine of a motor-car is coupled with the engine of that car during running of the same by means of a cog-wheel gearing or a chain and chain-wheel gearing or the like, its rotatory speed varies in the same measure as that of said engine. There occur, as a matter of course, only accelerations which, as regards for instance the Bendix starter have the tendency to make the pinion approach the fly-wheel, and if these members then come, perhaps, in contact with each other or, worse, mesh with each. other, it is unavoidable that damage will be done to the device. 4

With my improved starter no damage can occur, in that the pinion cannot possibly be pushed forward as long as the starter is 'I'Otating with a certain minimum number of rotations, and if .shortly prior to the'stopping of the motor the stop mechanism becomes again active detrimental consequences are rendered impossible owing to the particular construction of the stop mechanism.

The problem of obviating the drawbacks of the two starting systems above mentioned has been solved in the present inventionby combining a return spring which counteracts the forward movement vof the pushed screw member from its initial position, with a stop mechanism controlled by the rotary speed of said pushed screw member, that stop mechanism preventing, or limiting'to a certain small amount, the rotation of the said pushed screw member during the first part of its forward movement from rest intoits initial position, and being, moreover, so designed that it acts as stop mechanism only counter to small forces, whereas larger forces annul its effectiveness.

This combination which constitutes the main part ofmy invention I have still supplemented by a particular design of certain...

details wherein resides another part of this invention and which consists therein that the transmission of the power from the electromotor to the pinion holder and from this to the pinion is effected by the simples means imaginable.

A certain part of these details is known and consists in the feature that the pinion is axially shiftable relatively to the pushed screw member and counter to the action of a spring in the direction of the return movement of said screw member so that the pinion when contacting with the fiy-wheel while the pushed screw member is pushed forwardly can recede relatively to the said screw member. And in order to cause the pinion to turn, while it recedes from the screw member, until its teeth arrive in front of gaps between teeth of-the fly-wheel, the stop mechanism is, as will be described later on, provided with a sliding facejnclined relatively to the axis. 1

The pushed screw member I provide preferably with a forked end and the pinion with a catch face fitting into that forked end. A box-shaped sheet-metal member enclosing a part of the stop mechanism is screwed centrically upon the forked end of the pushedscrew member and reinforces it.

Preferably I make use, in the combination-in question of a stop mechanism comprising a stoplocated near the periphery of the pushed screw member and attached to the frame of with the device, and a finger carried by the pushed screw member .and being controlled, as regards its position, by the rotary speed of said latter member, and so arranged as to be able to contact with said stop. The finger and the stop are so shaped that the former gets out of the range of the latter when the pushed screw member has been moved forward for a certain length from its initial position. The finger is, besides, connected in such a manner with a weight adjustable by centrifugal force that it will be withdrawn from the range of the said stop when the pushed screw member rotates with a certain low speed.

Finally, either the said finger or the said stop, preferably, solely this latter, is so shaped that it prevents rotation of the pushed screw member only if the turning moment is con'iparatively small, whereas if it is large the finger or the stop yields so much that the stop mechanism becomes inactive.

The invention is-illustrated diagrammatically and by way of example on the accompanying drawings, on which Figure 1 is an axial section of a starter that embodies only the main portion of my invention, Figure 2 a transverse section of-the same starter along the line .A-B of Fig. 1, Figure 3 an axial sectionfof another form of starter embodying the invention, 'with an inclined slide surface in the stop mechanism, Figure 4 a planof the same device, Figure 5 an axial section of a starter, essentially similar to the device shown in Figs. 3' and 4, but modified in constructional .details, connected to an electric motor, Figure 6 a partial axial section of the starter alongthe line EF of Fig. 7, Figure 7 .a transverse section of the same starter along the line AB of Fig. 5, Figure 8 a partial plan of the same starter, and Figures 9, 10 and 11 show some details of the starter shown in Figs. 5, 6,7 and 8.

In the construction illustrated in Figs. 1, 2, 5, 6, 7 and 8 the screw gear with the pinion is arranged close to the bearing bracket of the electric machine. In the construction illustrated in Figs. 3 and 4 the parts mentioned of the starter are disposed at a' dis tance from the electric machine to which The pinion is an integral part of the nut of fiy-wheel of the combustion'engine.

the screw gear, the spindle 4 of which is a prolongation of the shaft of the electric motor. In this case the spindle 4 is accordingly the pushing screw member, and the nut and pinion 2 the pushed screwmember. The spindle 4 at itsexternal end has a smooth part 5 with a-journal 6 which fit into the bush 8'of a bearing 9. 7 is the r; turnspring having one of its ends fixed to he part 5 of the spindle4 a d the other end to the pinion 2. The spring 7 tends to hold the pinion in the initial position shown in the drawing. The end position of the pinion is determined by the shoulder of the spindle. 10 is a box like part; it is screwed on to the pinion and serves as a carrier and case for the speed controlled parts of the stop mechanism. sists of a lever 13, fixed )ivotally at 11 on to the part 10 and provi ed with a weight 12 and with the finger 14 which projects outwards through an opening 15 in the box 10. The stop mechanism also comprises a number of, for example, four stops 17 fixed near the circumference of the part 10 to the frame of the device which in this case is the bearing bracket of the electric motor 1. A spring 18 which is stretched between the part 10 and the weight 12 tends to hold the lever 13 in the position shown in the drawing and in this posit-ion the finger 14 can come into contact (touch) with one of the stops 17. 16 is a plate which is connected to the finger 14 and is adapted to cover the opening 15 and limits the outward movement of the finger. The stops 17 are pivotally fixed at 51 to )art 1 of the electric motor. A spring 52 having one end fixed to the part 1 of the electric motor and the other end to the stop 17 tends to push the part 17 of the stop against a pin 53.

The device works as follows: IVhen the electric motor 1 is switched on to the source of the current, usually an accumulator, the spindle 4 commences to rotate in the direction indicated by the arrows. The pinion 2 cannot rotate with it becauseit is held fast by the stop 17 by means of the finger 14, the spring 52 being sufiiciently strong to withstand the effort of the finger 14. The pinion 2 consequently moves forward to the left from its initial position shown in Fig. 1, thereby compressing the return spring 7. \Vhen the pinion has thus completed the first stage of its advance and the teeth of the pinion have entered the gaps in the teeth of the'fly-wheel 3, the finger 14 slides away in any axial direction from the stop 17. The further advance movement of the pinion 2 is now ensured by the fly wheel 3. The pinion 2 finallyreaches its end position at the shoulder 5 and is thereby coupled with the spindle 4 and adapted to rotate the fly wheel 3. When the engine is running under its own power the pinion 2 is accelerated.

relatively to the spindle 4 and owing to this acceleration as also to the effect of the return spring 7 the pinion 2 is brought back again its initial position. But at the moment that the pinion 2 has become coupled at its end position with the spindle 4, for rotating with it, the finger 14 must he moved to a position beyond the extent of the stops 17. This is effected by centrifugal force acting on the weight-12 against the tension of the This stop mechanism con-- spring 18, such force serving to move the weight 12 outwards with the result that the 'fingerl4 moves inwards and beyond reach of the stops 17. This condition holds so long as the spindle 4 rotates. The pinion 2 can therefore return without hindrance from the stop mechanism to the initial position. The stop mechanism does not come into effect again until the armature of the electric motor 1 approaches cessation of movement. With a low rotating speed ofthe armature the power .of the spring 18 begins to overcome the centrifugal force of the weight 12, thereby the finger 14 is again moved outwards and the stop mechanism again becomes operative.

If the starting procedure is initiated at a point of time, in which the fiy-wheel of the explosion motor is in motion, the pinion will be seized by the teeth of the fly-wheel as long as it is prevented from rotation by the stop mechanism. As the spring 52 is so designed that it can resist the small turning moment exerted upon it when the starting proceeds in the proper manner, whereas it gives way to stronger forces, the stop 17 will in this case simply be shoved aside, com-- pressing the spring 51, so that any damage is completely prevented.

The same is the case if the starting device is driven b a combined lighting-startingmachine. f with such an arrangement the explosion motor is disconnected and its number of revolutions becomes smaller and smaller, then the stop mechanism will again become active at a certain small number of revolutions of the lighting-starting-machine. As, owing to the influence of the fly-wheel of the machine, its speed decreases to zero only slowly, the pinion Will be again pushed forward and engage the still rotating flywheel, while it is still prevented from rotation by the stop mechanism. Also in this case the force of the spring 51 will be overcome by the strong turning moment of the flywheel, and owing thereto the stop 17 will be shoved aside and the stop mechanism become inactive. Without this elasticity of the stop 17 it would be quite impossible to use the starting device described in connection with a combined lighting-startingmachine.

In the starter, illustrated in Figs. 3 and 4 5 is a hollow shaft which at its right hand end is coupled to the armature of the electric motor (not shown) or of a combined electric starting and generating machine (not shown) and at the other end shown in the drawing the shaft is enlarged to form two chambers. In the first chamber, in close connection with the shaft, the nut 32 is arranged, which inthis instance represents the pushing screw member. In the second large chamber is arranged the hollow cylindrical head 20 of the spindle 19, which in this instance represents the pushed screw member. The right end (not shown) of the return spring 7 is secured to the shaft 5. The other end is fixed to the smooth portion 21 of the spindle 19. The spring tends to draw the spindle 19 and the parts connected with it into the shaft 5, that is, to the right of Fig. 3. The end of the shaft 5, which encloses the head 20 of the spindle 29, is arranged as a journal in the bush 28 of a fixed bearing 29 with a capped nut 26. This nut reaches to the bush 28, and, in cooperation with flange 27 of the shaft 5, prevents axial displacement of the shaft relatively to the bearing 29. The inner bore of the capped nut 26 fits loosely round the head 20. The diameter of this head is less than that of the chamber in which it is placed and the head has at its inner end a flange 30. Consequent ly there is between the inner 'wall of the chamber and the outer wall of the head 20 an annular space in which the shock absorbing spring 31 is placed.

The pinion with its short shaft 22 is axially displaceable but not rotatablymounted relatively to the bore of thehead 20, rotation is prevented by means of the'key 23 and keyway 23 in the head 20. In a cavity ,in the shaft 23 is the spring 24 which rests on the bottom of the bore of the head '20 and tends to push the shaft 22 with the pinion 2 out of the head. This outward movement is limited by the head of the screw 25 which is,screwed into the spindle 19. A.certain amount of inward movement of the shaft and pinion, under the compression of the spring 24 is possible, because at the extreme end of the pinion shown in the drawing a space is left between the bottom of the bore of the head 20 and the innerend of the shaft 22. I

' The speed controlled stop mechanism is constructed essentially as in the starter illustrated by Figs. 1 and 2. The box shaped part 10 with the parts 11 to 16 (see Fig. 2)

is screwed onto the spindle head 20. The

stops ITare secured tdthe bearing, 29. But, a

f as may be seen in Fig. 4, the finger 14 and the sto 17 are obliquely arranged, so that the sur ace, alongwhich the finger 14, when the pushed screw member is advancing, (towards the left hand of Fig. 4) can slide off the stop',17, is inclined relatively to the axis of the device. 4

The working of ,the device shown in- Figs. 3 and 4 is as follows: In consequence of the inclined glide surface between the finger 14 and the stop 17 the pushed screw member, the spindle 19 and the parts connected to it, particularly the pinion 2' and the part 10, make a slight rotation in the direction indicated'by the arrow (see Fig. 4) when the pushed screw -member advances from its initial position,

shown in Fi g. 3. If in .so doing a tooth of the pinion 2 strikes against a tooth of the fly-wheel 3, (as represented in Fig. 4), the

mesh with the fly-wheel. Ihe further action,

of the gear is the same as described above.

In Fig. 5 33 is the casing of the electric motor, 34 are the poles, 35 the exciting coils. 36 is the armature with its windings 37 and its commutator 38. 39 are the brushes.

The pinion consists in this case of three parts, viz, the toothed part 2 at the one end, a part 50 located in'the centre portion and provided with catch faces 50, and a hollow cylindrical shaft, 22 at the other end. This shaft and the pinion lie axially shiftable in a bore 40 of a pinion'holder, and this holder consists also of three parts, viz, a screwthreaded central part 19, a forked part 20 located at the front end and provided with catch faces 20 and intended to receive the central part 50 of the pinion, and a cylinthe thin lug 21 is fastened the return spring 7, the other end of which is connected with "the other end of the hollow shaft by means of an adjustable intermediate member 43. That end of the hollow shaft 5 which forms the chamber 41 is supported centrically'in the bearing flange 1 by means of aball bearing 44. The flange 1 carries also four abutment members 17 supported on pivots'51, and these abutment.members form flat an gles, of which the one leg 17 is located obliquely with respect to the axis of the starter and constitutes the stop proper, whereas the other leg 17. is'press'ed against the flange 1 by flat springs 52. The member 10 intended to receive the speed controlled stop mechanism is also in this case box-shaped and has a circular cavity with which it can be screwed centrally upon the end of the forkshaped part 20 of the pinionholder. An aperture in the plane wall of the part 10 has the profile of the-catch member 50 so that this member. an be axially shifted in said aperture. The box 10 encloses within it the parts 11 16 of the Figs. 1-4. The

pinion is represented perspectively in Fig. 9, the box 10 in Fig 10, and the pinion holder 19/20/21 in Fig. 11, in order to show still more distinctly the particular construction of the starter in question. I 4

The manner of operation of the starter illustrated in Figs. 511 will be clear without further details in View of what has already been explained on the preceding pages.

I claim:

1. An electric starter for explosion engines, especially for motor cars, comprising an electric motor, a pinion and a screw gear, a pushing member forming a part of said gear and .being connected to the motor, and a pushed member forming also a part of said gear and being connected to the pinion, a return spring adapted to counteract the advance of said pushed screw member out of its initial position, and a stop mechanism comprising stops fixed to the frame of the device near the circumference of the pushed screw member, and a finger so carried by the aforesaid screw member that it can engage said stops when the screw memberis Within the first part of its forward movement, springs, said stops being pivotally mounted and subjected to the pressure of said springs this latter being of such a strength as to be adapted to cause said finger to be retained by said stops only if a comparatively weak force acts upon it, whereas in the case of a stronger force said stops overcome the pressure of said springs and yield and release the said finger so as to permit it to rotate.

2. An electric starter for explosion engines, especially for motor cars, comprising an electric motor, a pinion and a screw gear, a pushing member forming a part of said gear and being connected to the motor, .and a pushed member forming also a part of said gear and being connected to the pinion, a return spring adapted to counteract the advanceof saidpushed screw member out of its initial position, and a stop mechanism dependent upon the rotary speed of said pushed screw member and adapted to prevent or to limit to a very small amount the rotation of the pushed screw member during the first part of its advance from rest in its intial position, said stop mechanism comprising stops fixed to the frame of the device near the circumference of the pushed screw member, and a finger so carried by the aforesaid screw member that it can engage said stops when the screw member is within the first part of its forward movement, springs, said stops being pivotally mounted and subjected to the pressure of said springs this latter being of such a strength as to be adapted to cause said finger to be retained by said stops only if a comparatively weak force acts upon it, whereas in the case of a stronger force said stops overcome the pressure of said springs and yield and release the said finger so as to permit it to rotate, another spring, an ax ially displaceable pinion mounted on the pushed screw member and held in its normal position by said other spring, an inclined glide surface on said stops, this gliding surface being so inclined relatively to the axis of the device, that a slight rotation is imparted to the pushed screw member during its advance through the engagement of the stop and finger.

3. An electric starter for explosion engines, especially for motor cars, comprising an electric motor, a pinion and a screw gear, a pushing member forming a part of said gear and being connected to the motor, and a pushed member forming also a part of said gear and being connected to the pinion, a return spring adapted to counteract the advance ofsaid pushed screw member out of its initial position, and a stop mechanism dependent upon the rotary speed of said pushed screw member and adapted to prevent or to limit to a very small amount the rotation of the pushed screw member during the first part of its advance from rest in its initial position, said step mechanism comprising stops fixed to the frame of the device near the circumference yield and release the said finger so as to permit it to rotate, the said pushing member comprising a hollow shaft and-a nut and the said pushed member comprising a pinion holder screwed into said nut and a pinion axially shiftable in said holder, a divided ring adapted to transmit the power from said hollow shaft to said pinion and being located in an annular groove of the said pinion holder and to abut on said nut.

4. An electric starter for explosion engines, especially for motor cars, comprising an electric motor, a pinion and a screw gear, a pushing member forming a part of said gear and being connected to the motor, and a pushed member forming also a part of said gear and being connected to the pinion, a return spring adapted to counteract the advance of said pushed screw member out of its initial position, and a. stop mechanism dependent upon the rotary speed of said pushed screw member and adapted to prevent or to limit to a very small amount the rotation of the pushed screw member during the first part of its ad- Vance from rest in its initial position, said stop mechanism comprising stops fixed to the frame of the device near the circumference of the pushed screw member, and a finger so carried by the aforesaid screw member that it can engage said stops when the screw mem-' ber is within the first part of its forward movement, springs, saidstops being pivot ally mounted and subjected to the pressure of 10 said springs this latter being of such a strength as to be adapted to cause said dinger to be retained by said stops only if a comparatively weak force actsupon it, whereas in the case of a stronger force said stops overcome the pressure of said springs and yield andrelease the said finger so as to permit it to rotate, the said pushing member comprising a hollow shaft and a nut and the said pushed member comprising a pinion holder screwed into said nut and a pinion axially shiftable in said holder, adivided 1mg adapted to transmit the power from said hollow shaft to said pinion holder and being located in an annular groove of said pinion holder andto abut on said nut, and catching faces provided on thepinion holder and the pinion and adapted to transmit the power.

FRITZ KESSELRING. 

